Manufacture of refractory bricks or the like from chrome ore



atented Sept. 18,1934

UNITED STATES MANUFACTURE OF REFRACTORY BRICKS OB THE LIKE FROM ORE Elisabeth Luz, Essen-Ruhr, Germany, assignor,

by mesne assignments, to TheKoppersCompany of Delaware, Pittsburgh, Pa., a corporationof Delaware No Drawing. Application January 25, '1932,

Serial No. 588,829. In Germany January 24.

6 Claims. (01. 25-156) (Granted under the provisions of sec. 14,

- March 2, 1927; 357 O. G.

I'have illed an application in Germany on January 24, 1931.

The invention relates to the manufacture of refractory bricks and more particularly to the manufacture of refractory bricks or the like from chrome ore.

. It is well-known that the commercial chrome bricks generally suifer from their inability to support loads at high temperatures. It also is known that the ordinary chrome bricks only possess a low spelling resistance. One has already tried to improve the qualityof chrome ore bricks by adding to the refractory mass used for the manufacture of chrome ore bricks certain: substances.

l 'orinstance frommixtures of chrome ore and.

diaspore, bricks with relatively favourable qualitlos have been manufactmfed, which are better able to withstand any sudden change of temperature than bricks made from chrome ore.

The first object of my present invention is to provide an improved method for making chrome ore bricks by which it is rendered possible to manufacture chrome ore bricks which are not only able to stand better rigid thermal change but also temperatures.

A further object of my present invention is to provide an improved refractory mass suitable for the manufactiu'e of highly refractory! chrome bricks, which are able to stand better sudden changes of temperatures and show an improved load bearing capacity at high temperatures.

Finally, an object of my invention is refractory bricks or the like from chrome ore, which are able to stand better sudden changes of temperature and show an improved load bearing capacity at high temperatures.

With these and other objects of my invention in view I will now describe the nature of my present invention more fully in details.

I have found that certain slags which are recovered as waste products from the manufacture of ferro-chromium and ferro-vanadium by the so-called thermite-process in a proportion of 10 to 40 per cent added to the chrome ore mass are suitable to raise essentially the softening point of chrome ore bricks under a load of about lbs. per sq. inch, whereby at the same time the ability of the bricks to withstand changes of tem-- peratures is considerably increased.

Refractory bricks made of chrome are alone generally fail suddenly under load of 50 lbs. at M50 C. or less. temperature could be raised by an addition oi 10% of the above mentioned dogs to about 15W) o, by an addition oi a out show an improved load bearing capacity at high act of 20% to about 1650 C. and by an addition of 30% of the above mentioned slags above 1700 C. The herein mentioned indications of temperature refer to degrees centigrade. The slag. used by me as an addition to th chrome ore has generally a content of approximately 73% A120: andabout 23% mo together with asmall quantity of other constituents. The percentage of S102 in slag amounts to 1% or less.

I have further found that one can obtain the 65 same effect when making a chrome ore brick as with a slag from the ferro-chrome and ferrovanadium production also with other kinds of slag which contain only a small percentage of silica and up to or more of AlzOa+MgO together or under certain circumstances of AlzOa+MgO+CnOa to ether. 'I wish to charac terize those kinds of slag which are suitable of employment in the case of my present invention for the improvements of the-quality of chrome 7 are bricks in that the slag must consist essentiallyof m esia-alumina compounds, possibly also of chromium compounds, of which the contents of'magnesia may be lower than in the case of the corresponding spinel compound. 9

As to the percentage of slag in the manufacture of chrome ore bricks in single cases, this depends on to what degree ofresistance against heat the ready bricks should have or up to which point of temperature'the chrome ore brick may soften under'load, any mixture of chrome ore and the refractory slag being possible.

- For instance, according to my present inven-- tion, one may proceed to the manufacture of high refractory and temperature changes re v sisting chrome ore bricks as follows: 350 kilos chrome ore with about 40% CH0: and 150 kilos of a metallurgical slag with 73% A1203, 23% Mg0 and less than 1% s10: may be ground to a grain size under 3 mm. and mixed in a wet pan with the addition of 4% of water and a small quantity of a customary organic cleaving mixture for instance dextrine. The ready mixed mass may be shaped by pressing or in any other suitable manner and the shapes are thereupon dried and finally burned in usual manner at temperatures of about 1450 C. to 1500 C. The ready brick can resist under a load cl 50 lbs. per sq. inch'up to a temperature of 5 about 17% C.

I wish to be understood that I do not w. 111 my invention to the exact details described, but that it may be varied wit the scope oi the cl or s hereinafter made.

I claim:

1. The method for manufacturing refractory bricks or the like from chrome ore comprising adding to between 90% and 60% of reduced chrome ore of about CrzOs, between 10 and 40 of reduced metallurgical slag recovered as a waste product of a metallurgical process and consisting of not less than substantially 90% of magnesia and alumina and not more than 1% of silica, adding further a liquid, moulding the mass into shapes and finally burning said shapes.

2. The method for manufacturing refractory bricks or the like from chrome ore comprising adding to chrome ore metallurgical slag recovered as a waste product of a metallurgical process and consisting of not less than substantially 90% of magnesia and alumina and not more than 1% of silica, adding further a liquid, moulding the mass into shapes, drying said shapes and finally burning same.

3. The method as set forth in claim 2, wherein as addition to the chrome ore the slag used is one which is obtained by the so-called thermiteprocess for manufacturing term-vanadium or ferro-chromium.

4. Refractory mass for the manufacture of highly refractory chrome bricks comprising between 90% and chrome ore of about 40% CIzOa, and between 10 and 40% of a metallurgical slag recovered as a waste product of a metallurgical process, said slag consisting substantially of at least 90% of magnesia and alumius. and not more than 1% of silica, and a liquid.

5. Refractory mass for the manufacture of highly refractory chrome bricks comprising between 90% and 60% chrome ore of about 40% CrzOa, and between 10 and 40% of a metallurgical slag which is obtained as a waste product from the so-called thermite process for the production of ferro-chrcmium or ferro-vanadium and having a content of about 73% A120: and 23% MgO and not more than 1% of silica, and a liquid.

6. Highly refractory brick made from a mass as described in the claim 5, said mass having been moulded into shapes and finally burned.

ELISABETH LUX. 

